IAEA uses nuclear detection techniques to help measure climate change effects

Nitrous oxide (N2O) is a greenhouse gas that has 298 times more global-warming potential per unit mass than CO2, and is naturally produced in soils during the microbial processes of nitrification, co-denitrification and denitrification. “We can use nuclear techniques to determine whether N2O is produced from the nitrogen in fertilizers or from nitrogen in the soil,” Pérez explained. It is known from 15N measurements that of total N2O emissions, 10 to 40 percent can be attributed to fertilizers and 60 to 90 percent originate from the soil, Pérez added.

Real change for climate change
These new data, specific to Costa Rica, will help to design policy change in the country. Greenhouse gas emissions, and in particular the effects of fertilizers, form the basis of cost-benefit calculations that can be used to determine the right amount and kind of fertilizer to be applied in order to move towards carbon neutrality in the dairy sector.

The project is helping to bring about change with the involvement of the private sector through lectures and field studies at the University of Costa Rica and through the joint Livestock Commission of the Program of Research and Transference of Technology.

The project in Costa Rica is one of many ongoing coordinated research projects run by the IAEA in cooperation with the Food and Agriculture Organization of the United Nations (FAO) that focus on reaching a more accurate and complete understanding of greenhouse gas emissions around the world, said Mohammad Zaman, a soil scientist at the Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture. Besides Costa Rica, the project also helps scientists from Brazil, Chile, China, Estonia, Ethiopia, Germany, Iran, Pakistan, and Spain to enhance their ability to measure greenhouse gas emissions with greater precision as well as identify their exact source of production in soils, in order to apply mitigation measures, Zaman said.

The Science: Using isotopes to study greenhouse gas production
Isotopes are chemical elements (like carbon or nitrogen) that have the same number of protons but a different number of neutrons. Though isotopes chemically react in the same way, their differing atomic weights make it possible to distinguish between them. By using isotopes as tracers, scientists can track how elements move through complex cycles and see how they’re involved in the production of specific molecules like those in greenhouse gases.

In the case of N2O, scientists can analyze isotopomers (molecules with the same number of isotopes of each element but in chemically different positions) in nitrification, denitrification and co-denitrification processes within soil to study how nitrogen-based molecules change in these processes and what individual factors influence the production of this potent greenhouse gas.